(CNN) -- It was called the "Twitter Revolution" -- the mass street protests following Iran's questionable June elections that were beamed to the world via social media and other online tools despite the government's media blackout.
This week, a loose, multi-national network of protesters, bloggers, Web developers and everyday Internet users has ramped up again in the wake of renewed anti-government street demonstrations that turned deadly Sunday on Ashura, a Shiite Muslim holy day commemorating the death of 7th Century cleric Imam Hussein.
This time, Internet analysists and online activists involved in the movement have told CNN that a government initially caught flat-footed at how easily information flowed out of the country was ready to fight back.
"It's clear the government has been definitely restricting the Internet in a much more controlled way," said Cyrus Farivar, an Iranian-American freelance journalist who writes about technology issues. "They're definitely paying attention and, at the very least, trying to intimidate people."
And retaliation has been brutal -- both for those taking to the streets and those spreading the word online.
One of the most compelling videos to emerge from the recent unrest showed what the people who posted it said was an Iranian government vehicle plowing into a crowd of protesters, apparently running over and, they say, killing a woman.
Abbas Jafari Dolatabadi, Tehran's chief prosecutor, said Tuesday that seven people were killed in the Ashura riots. The demonstrations were the deadliest since June. Those left at least eight dead, according to Iran's Supreme National Security Council -- although dissidents and observers have said there were many more.
The world was able to learn about those protests through first-person accounts online after a disputed election that returned hard-line President Mahmoud Ahmadinejad to office despite serious questions about polling results.
As protests swelled, Iran's government began kicking out some reporters from some traditional Western media outlets, arresting others and restricting the movements of those who remained.
In their place sprung citizen journalists who posted videos, photos and firsthand accounts on Twitter feeds, Facebook groups and sites like Flickr and YouTube. They kept images of the protests -- and the sometimes bloody response of government backers -- in front of the world.
As early as election day, both opposition political leaders and anti-government protesters said cell-phone signals were being jammed. They consistently reported networking Web sites in Iran being blocked, phone lines disconnected and protest sites allegedly infiltrated by government spies who spread misinformation and sought the identities of those speaking against the regime,
That experience, observers say, had the government primed for the most recent explosion of information.
"The spike at the beginning, right after the election, was pretty chaotic,"said Austin Heap, a San Francisco-based Web developer who has helped Iranian dissidents report from within their country. "Not even their government knew what they were going to do and how they were going to handle things.
"I think right now what you're seeing is a much more coordinated and organized response from them."
Tech experts say the Iranian government has become more adept at using a type of Internet filtering called deep-packet inspection to track information sent from one Internet user to another and hunt down the sender.
The government has also begun using the protest's own techniques against it. As early as June, online activists said they suspected government agents of posing as protesters in an attempt to pry information out of people within the movement. Some Twitter feeds of protesters suddenly and inexplicably began posting pro-government messages or asking for details about where and when protests would be held.
Earlier this month, videos that appeared to show protesters burning an image of Supreme Leader Ayatollah Ali Khamenei circulated the Internet. Opposition leaders denied the burnings ever happened and said they were a hoax carried out by the government to discredit them and turn the Iranian public against their cause.
"Fake clips, usually made to provoke and split the opposition, are becoming a staple of the Iranian Internet," Evgeny Morozov, who writes about the Internet for Foreign Policy magazine, wrote in a commentary for CNN.
Austin Heap has helped set up and verify reliable proxies by which Iranians can post news to the Web without giving away their locations. He's also helping develop a program called Haystack designed to help Iranians anonymously elude government filters.
"We definitely have been working on overload for the past three days," he said Tuesday. "I woke up two days ago to 60 e-mails and 12 missed phone calls -- all people that, all of a sudden, needed an immediate response."
The continued media blackout in Iran had made it difficult for traditional media to immediately verify Sunday's accounts of the weekend's violence. But videos that surfaced depicted bloodied and, in some cases, apparently dead protesters.
A range of Web sites have either emerged or seen renewed interest in light of the recent protests. They run the gamut from YouTube accounts dedicated to images from street protests to blogs mocking the Iranian regime.
At the blog Watch Me Confess, opponents of Iran's government post faux apologies for what they call ridiculous claims the government has made about the protesters.
At Neda Net -- named for the young woman whose shooting death in June became a rallying cry for protesters -- people who call themselves a network of hackers offer tips on how to help Iranians use the Internet freely
"There's this kind of global attention being paid across different countries and cultures and languages," said Farivar, who noted the emergence of a Twitter hashtag -- #CN4Iran -- THAT appears to have been started by Chinese supporters of the Iranian protesters.
Despite their best efforts and good intentions, supporters outside the country won't decide the outcome of the most recent round of protests, Farivar said. The actions of Iranians on the ground will.
"I think it's naive to think that just because you're changing your location to Tehran [on a Twitter profile] that you're confusing the Iranian authorities," he said. "That would make them seem less intelligent than they are."
But Heap said the steady flow of information will be important as a government that prefers secrecy continues a violent crackdown on its citizens.
"They can't hide any more," he said. "The government has done everything they can to shut people up, and every time they do this they're just making more and more activists -- more and more citizen journalists."